Perceptual equivalence of the Liljencrants-Fant and linear-filter glottal flow models

Speech glottal flow has been predominantly described in the time-domain in past decades, the Liljencrants-Fant (LF) model being the most widely used in speech analysis and synthesis, despite its computational complexity. The causal/anti-causal linear model (LF_CALM) was later introduced as a digital filter implementation of LF, a mixed-phase spectral model including both anti-causal and causal filters to model the vocal-fold open and closed phases, respectively. To further simplify computation, a causal linear model (LF_LM) describes the glottal flow with a fully causal set of filters. After expressing these three models under a single analytic formulation, we assessed here their perceptual consistency, when driven by a single parameter R_d related to voice quality. All possible paired combinations of signals generated using six R_d levels for each model were presented to subjects who were asked whether the two signals in each pair differed. Model pairs LF_LM-LF_CALM were judged similar when sharing the same R_d value, and LF was considered the same as LF_LM and LF_CALM given a consistent shift in R_d. Overall, the similarity between these models encourages the use of the simpler and more computationally efficient models LF_CALM and LF_LM in speech synthesis applications.

Vocal fold dynamics in a synthetic self-oscillating model: Intraglottal aerodynamic pressure and energy

Self-sustained oscillations of the vocal folds (VFs) during phonation are the result of the energy exchange between the airflow and VF tissue. Understanding this mechanism requires accurate investigation of the aerodynamic pressures acting on the VF surface during oscillation. A self-oscillating silicone VF model was used in a hemilaryngeal flow facility to measure the time-varying pressure distribution along the inferior-superior thickness of the VF and at four discrete locations in the anterior-posterior direction. It was found that the intraglottal pressures during the opening and closing phases of the glottis are highly dependent on three-dimensional and unsteady flow behaviors. The measured aerodynamic pressures and estimates of the medial surface velocity were used to compute the intraglottal energy transfer from the airflow to the VFs. The energy was greatest at the anterior-posterior midline and decreased significantly toward the anterior/posterior endpoints. The findings provide insight into the dynamics of the VF oscillation and potential causes of some VF disorders.

A Deep Learning Enhanced Novel Software Tool for Laryngeal Dynamics Analysis

Purpose High-speed videoendoscopy (HSV) is an emerging, but barely used, endoscopy technique in the clinic to assess and diagnose voice disorders because of the lack of dedicated software to analyze the data. HSV allows to quantify the vocal fold oscillations by segmenting the glottal area. This challenging task has been tackled by various studies; however, the proposed approaches are mostly limited and not suitable for daily clinical routine. Method We developed a user-friendly software in C# that allows the editing, motion correction, segmentation, and quantitative analysis of HSV data. We further provide pretrained deep neural networks for fully automatic glottis segmentation. Results We freely provide our software Glottis Analysis Tools (GAT). Using GAT, we provide a general threshold-based region growing platform that enables the user to analyze data from various sources, such as in vivo recordings, ex vivo recordings, and high-speed footage of artificial vocal folds. Additionally, especially for in vivo recordings, we provide three robust neural networks at various speed and quality settings to allow a fully automatic glottis segmentation needed for application by untrained personnel. GAT further evaluates video and audio data in parallel and is able to extract various features from the video data, among others the glottal area waveform, that is, the changing glottal area over time. In total, GAT provides 79 unique quantitative analysis parameters for video- and audio-based signals. Many of these parameters have already been shown to reflect voice disorders, highlighting the clinical importance and usefulness of the GAT software. Conclusion GAT is a unique tool to process HSV and audio data to determine quantitative, clinically relevant parameters for research, diagnosis, and treatment of laryngeal disorders. Supplemental Material https://doi.org/10.23641/asha.14575533.

Computational simulations of respiratory-laryngeal interactions and their effects on lung volume termination during phonation: Considerations for hyperfunctional voice disorders

Glottal resistance plays an important role in airflow conservation, especially in the context of high vocal demands. However, it remains unclear if laryngeal strategies most effective in controlling airflow during phonation are consistent with clinical manifestations of vocal hyperfunction. This study used a previously validated three-dimensional computational model of the vocal folds coupled with a respiratory model to investigate which laryngeal strategies were the best predictors of lung volume termination (LVT) and how these strategies' effects were modulated by respiratory parameters. Results indicated that the initial glottal angle and vertical thickness of the vocal folds were the best predictors of LVT regardless of subglottal pressure, lung volume initiation, and breath group duration. The effect of vertical thickness on LVT increased with the subglottal pressure-highlighting the importance of monitoring loudness during voice therapy to avoid laryngeal compensation-and decreased with increasing vocal fold stiffness. A positive initial glottal angle required an increase in vertical thickness to complete a target utterance, especially when the respiratory system was taxed. Overall, findings support the hypothesis that laryngeal strategies consistent with hyperfunctional voice disorders are effective in increasing LVT, and that conservation of airflow and respiratory effort may represent underlying mechanisms in those disorders.

Semi-occluded vocal tract exercises in healthy young adults: Articulatory, acoustic, and aerodynamic measurements during phonation at threshold

Semi-occluded vocal tract exercises (SOVTEs) are increasingly popular as therapeutic exercises for patients with voice disorders. This popularity is reflected in the growing research literature, investigating the scientific principles underlying SOVTEs and their practical efficacy. This study examines several acoustic, articulatory, and aerodynamic variables before, during, and after short-duration (15 s) SOVTEs with a narrow tube in air. Participants were 20 healthy young adults, and all variables were measured at threshold phonation levels. Acoustic variables were measured with a microphone and a neck accelerometer, and include fundamental frequency, glottal open quotient, and vocal efficiency. Articulatory variables were measured with ultrasound, and include measures of the tongue tip, tongue dorsum, and posterior tongue height, and horizontal tongue length. Aerodynamic variables were measured with an intraoral pressure transducer and include subglottal, intraoral, and transglottal pressures. Lowering of the posterior tongue height and tongue dorsum height were observed with gender-specific small changes in the fundamental frequency, but there were no significant effects on the transglottal pressure or vocal efficiency. These findings suggest that the voices of healthy young adults already approach optimal performance, and the continued search for scientific evidence supporting SOVTEs should focus on populations with voice disorders.

Comparison of Glidescope Core, C-MAC Miller and conventional Miller laryngoscope for difficult airway management by anesthetists with limited and extensive experience in a simulated Pierre Robin sequence: A randomized crossover manikin study

BACKGROUND

Video laryngoscopy is an effective tool in the management of difficult pediatric airway. However, evidence to guide the choice of the most appropriate video laryngoscope (VL) for airway management in pediatric patients with Pierre Robin syndrome (PRS) is insufficient. Therefore, the aim of this study was to compare the efficacy of the Glidescope® Core™ with a hyperangulated blade, the C-MAC® with a nonangulated Miller blade (C-MAC® Miller) and a conventional Miller laryngoscope when used by anesthetists with limited and extensive experience in simulated Pierre Robin sequence.

METHODS

Forty-three anesthetists with limited experience and forty-three anesthetists with extensive experience participated in our randomized crossover manikin trial. Each performed endotracheal intubation with the Glidescope® Core™ with a hyperangulated blade, the C-MAC® with a Miller blade and the conventional Miller laryngoscope. "Time to intubate" was the primary endpoint. Secondary endpoints were "time to vocal cords", "time to ventilate", overall success rate, number of intubation attempts and optimization maneuvers, Cormack-Lehane score, severity of dental trauma and subjective impressions.

RESULTS

Both hyperangulated and nonangulated VLs provided superior intubation conditions. The Glidescope® Core™ enabled the best glottic view, caused the least dental trauma and significantly decreased the "time to vocal cords". However, the failure rate of intubation was 14% with the Glidescope® Core™, 4.7% with the Miller laryngoscope and only 2.3% with the C-MAC® Miller when used by anesthetists with extensive previous experience. In addition, the "time to intubate", the "time to ventilate" and the number of optimization maneuvers were significantly increased using the Glidescope® Core™. In the hands of anesthetists with limited previous experience, the failure rate was 11.6% with the Glidescope® Core™ and 7% with the Miller laryngoscope. Using the C-MAC® Miller, the overall success rate increased to 100%. No differences in the "time to intubate" or "time to ventilate" were observed.

CONCLUSIONS

The nonangulated C-MAC® Miller facilitated correct placement of the endotracheal tube and showed the highest overall success rate. Our results therefore suggest that the C-MAC® Miller could be beneficial and may contribute to increased safety in the airway management of infants with PRS when used by anesthetists with limited and extensive experience.

Fluid-structure-acoustic interactions in an ex vivo porcine phonation model

In the clinic, many diagnostic and therapeutic procedures focus on the oscillation patterns of the vocal folds (VF). Dynamic characteristics of the VFs, such as symmetry, periodicity, and full glottal closure, are considered essential features for healthy phonation. However, the relevance of these individual factors in the complex interaction between the airflow, laryngeal structures, and the resulting acoustics has not yet been quantified. Sustained phonation was induced in nine excised porcine larynges without vocal tract (supraglottal structures had been removed above the ventricular folds). The multimodal setup was designed to simultaneously control and monitor key aspects of phonation in the three essential parts of the larynx. More specifically, measurements will comprise (1) the subglottal pressure signal, (2) high-speed recordings in the glottal plane, and (3) the acoustic signal in the supraglottal region. The automated setup regulates glottal airflow, asymmetric arytenoid adduction, and the pre-phonatory glottal gap. Statistical analysis revealed a beneficial influence of VF periodicity and glottal closure on the signal quality of the subglottal pressure and the supraglottal acoustics, whereas VF symmetry only had a negligible influence. Strong correlations were found between the subglottal and supraglottal signal quality, with significant improvement of the acoustic quality for high levels of periodicity and glottal closure.

A one-dimensional flow model enhanced by machine learning for simulation of vocal fold vibration

A one-dimensional (1D) unsteady and viscous flow model that is derived from the momentum and mass conservation equations is described, and to enhance this physics-based model, a machine learning approach is used to determine the unknown modeling parameters. Specifically, an idealized larynx model is constructed and ten cases of three-dimensional (3D) fluid-structure interaction (FSI) simulations are performed. The flow data are then extracted to train the 1D flow model using a sparse identification approach for nonlinear dynamical systems. As a result of training, we obtain the analytical expressions for the entrance effect and pressure loss in the glottis, which are then incorporated in the flow model to conveniently handle different glottal shapes due to vocal fold vibration. We apply the enhanced 1D flow model in the FSI simulation of both idealized vocal fold geometries and subject-specific anatomical geometries reconstructed from the magnetic resonance imaging images of rabbits' larynges. The 1D flow model is evaluated in both of these setups and shown to have robust performance. Therefore, it provides a fast simulation tool that is superior to the previous 1D models.

[Study on the measurement of glottic proportion in subjects with normal larynx]

Objective:The aim of this study is to explore the glottic proportion（GP） and gender difference in Chinese subjects with normal larynx. Methods:Two hundred patients with normal larynx in Sixth Medical Center of PLA General Hospital from January 2017 to December 2019 were selected as the experimental group. Group 1 included 100 females and group 2 included 100 males. Sixty patients with normal larynx in the Pontes article were selected as the control group, including 30 females as group 3 and 30 males as group 4. Results:The GP range in group 1 was 0.78-1.76, with a mean of 1.24; 0.82-2.20 in group 2, with a mean of 1.37; 0.91-1.20 in group 3, with a mean of 1.04; 1.07-1.44 in group 4, with a mean of 1.21. Statistical analysis showed that the data of the four groups were normal distribution, the standard deviation was 0.16 in group 1, 0.26 in group 2, 0.08 in group 3, 0.10 in group 4, and the test of homogeneity of variance was P<0.05. Games-Howell test was used for multi-group analysis, including group 1 and group 2, group 3 and group 4, group 1 and group 3, group 2 and group 4. The statistical results of the four groups all showed P<0.05, indicating that there were statistical differences. Conclusion:On the whole, the average GP of male group was higher than that of female, but not all males have a greater GP value than females. In the range of high GP value, males accounted for a large proportion, while in the range of low GP value, females accounted for a large proportion. In the past, most articles regard men and women as two groups to study the glottic proportion, and it was suggested that more attention should be paid to individual differences when discussing glottic proportion and related laryngeal diseases.

[Endoscopic-assisted modified cricothyroid membrane approach for laryngeal surgery in patients with difficult airways]

Objective:To explore the value of endoscopic-assisted modified cricothyroid membrane approach laryngeal surgery in patients with difficult airways and evaluate its safety. Methods:All patients with laryngeal surgery who were hospitalized were evaluated. For the patients with difficult airways those could not be exposed through routine surgical approach, after full communication, we carried out the endoscope-assisted modified loop thyroscopic approach to the thyroid membrane. Results:All the 12 patients completed the operation successfully, and the visual field exposure was satisfactory during the operation. None of the patients had bleeding and glottic and subglottic stenosis after the operation, and the sound recovered satisfactorily. Conclusion:The cricothyroid membrane approach is not a routine choice for laryngeal surgery, but it is significantly better than other surgical methods for patients with difficult airways who are difficult to expose by conventional approaches, and it is a good choice for patients who cannot be exposed by conventional surgical approaches. The choice is worthy of clinical promotion.

[Application of videostrobokymography in analyzing factors affecting voice after surgery]

Objective:To elucidate the value of videostrobokymography in the evaluation of the characteristics of vocal cord vibration after the surgery. Methods:To analyze the spectrum of the voice before and after the microsurgery of the vocal folds. Using the videostrobokymography to reveal the changes of vibration, especially in the cases with poor spectrum elevation but without obvious recurrence. Results:Two patients were with elevated vocal parameters; 2 patients were with partially elevated vocal parameters（one with Jitter decreased while others elevated; one with Shimmer decreased while others elevated）; the other 3 patients were with decreased vocal parameters. The videostrobokynmography showed the recurrence in 1 patient, but not in others. In 4 cases with elevated vocal parameters, the videostrobokymography showed cycle-to-cycle variability of the amplitude, absence of vibration of vocal fold, glottal axis shift and phase difference . Conclusion:There are certain value of videostrobokymography in analyzing the minor changes of characteristic of vibration of vocal fold.

Glottal Aerodynamics Estimated From Neck-Surface Vibration in Women With Phonotraumatic and Nonphonotraumatic Vocal Hyperfunction

Purpose The purpose of this study was to determine whether estimates of glottal aerodynamic measures based on neck-surface vibration are comparable to those previously obtained using oral airflow and air pressure signals (Espinoza et al., 2017) in terms of discriminating patients with phonotraumatic and nonphonotraumatic vocal hyperfunction (PVH and NPVH) from vocally healthy controls. Method Consecutive /pae/ syllables at comfortable and loud level were produced by 16 women with PVH (organic vocal fold lesions), 16 women with NPVH (primary muscle tension dysphonia), and 32 vocally healthy women who were each matched to a patient according to age and occupation. Subglottal impedance-based inverse filtering of the anterior neck-surface accelerometer (ACC) signal yielded estimates of peak-to-peak glottal airflow, open quotient, and maximum flow declination rate. Average subglottal pressure and microphone-based sound pressure level (SPL) were also estimated from the ACC signal using subject-specific linear regression models. The ACC-based measures of glottal aerodynamics were normalized for SPL and statistically compared between each patient and matched-control group. Results Patients with PVH and NPVH exhibited lower SPL-normalized glottal aerodynamics values than their respective control subjects (p values ranging from < .01 to .07) with very large effect sizes (1.04-2.16), regardless of loudness condition or measurement method (i.e., ACC-based values maintained discriminatory power). Conclusions The results of this study demonstrate that ACC-based estimates of most glottal aerodynamic measures are comparable to those previously obtained from oral airflow and air pressure (Espinoza et al., 2017) in terms of differentiating between hyperfunctional (PVH and NPVH) and normal vocal function. ACC-based estimates of glottal aerodynamic measures may be used to assess vocal function during continuous speech and enables this assessment of daily voice use during ambulatory monitoring to provide better insight into the pathophysiological mechanisms associated with vocal hyperfunction.

Laryngeal tubes and laryngeal mask devices for supraglottic airway management in out-of-hospital emergency care: a systematic review

Various supraglottic devices are currently available for airway management and are used widely in emergency situations because they are easy to position. We undertook a systematic review of the literature comparing laryngeal tubes and various laryngeal mask airway devices (LMAs) to determine which ones can be used most efficiently in emergencies. Nine databases were searched, as follows: Cochrane Library Plus, MEDLINE, CINAHL (Cumulative Index to Nursing and Allied Health Literature), Dialnet, Global Health, Nursing & Allied Health Database, CUIDEN, the Web of Science, and ScienceDirect. We collected studies published between 2014 and 2019 in Spanish, English, French, and Portuguese that compared laryngeal tubes to LMAs of different types for supraglottic airway management. Eighteen studies were selected for analysis after critical reading. Significant differences were not seen between tubes and LMAs with respect to most variables, but in certain contexts the oropharyngeal seal and speed of insertion were superior with laryngeal tubes; however, when fiberoptic bronchoscopes were then inserted the view of the glottis was poor. The different contexts in which these devices are used and the scarcity of studies comparing laryngeal tubes to LMAs does not allow us to identify clear differences among them with respect to efficiency. However, tubes seem to offer poorer visibility of the glottis according to evaluation with fiberoptic scopes, a factor to bear in mind if tracheal intubation, which is considered the gold standard, might become necessary.

Indicators of anterior-posterior phase difference in glottal opening measured from natural production of vowels

Voiced speech is generated by the glottal flow interacting with vocal fold vibrations. However, the details of vibrations in the anterior-posterior direction (the so-called zipper-effect) and their correspondence with speech and other glottal signals are not fully understood due to challenges in direct measurements of vocal fold vibrations. In this proof-of-concept study, the potential of four parameters extracted from high-speed videoendoscopy (HSV), electroglottography, and speech signals to indicate the presence of a zipper-type glottal opening is investigated. Comparison with manual labeling of the HSV videos highlighted the importance of multiple parameter-signal pairs in indicating the presence of a zipper-type glottal opening.

Laryngeal strategies to minimize vocal fold contact pressure and their effect on voice production

The goal of this study is to identify laryngeal strategies that minimize vocal fold contact pressure while producing a target sound pressure level (SPL) using a three-dimensional voice production model. The results show that while the subglottal pressure and transverse stiffness can be manipulated to reduce the peak contact pressure, such manipulations also reduce the SPL, and are thus less effective in reducing contact pressure in voice tasks targeting a specific SPL level. In contrast, changes in the initial glottal angle and vocal fold vertical thickness that reduce the contact pressure also increase the SPL. Thus, in voice tasks targeting a specific SPL, such changes in the initial glottal angle and vertical thickness also lower the subglottal pressure, which further reduces the peak contact pressure. Overall the results show that for voice tasks with a target SPL level, vocal fold contact pressure can be significantly reduced by adopting a barely abducted glottal configuration or reducing the vocal fold vertical thickness. Aerodynamic measures are effective in identifying voice production with large initial glottal angles, but by themselves alone are not useful in differentiating hyperadducted vocal folds from barely abducted vocal folds, which may be better differentiated by closed quotient and voice type measures.

Changes in the voice production of solo singers across concert halls

To investigate the influence of room acoustics on singing, four lyrical singers (soprano, mezzo-soprano, tenor, baritone) performed four musical pieces in eight different venues (from dry studio to reverberant church). In addition to vocal intensity measured by a near-field microphone, glottal behavior (vibratory fundamental frequency and contact quotient) was assessed by electroglottography. Statistical linear mixed models showed that the variance in vocal performance was partly explained by room acoustics. Complementary to previous results on voice musical features influenced by timbre and level of the room's response, voice production parameters were mostly influenced by spatial aspects of the room's response.

Analysis of the tonal sound generation during phonation with and without glottis closure

The human phonation is characterized by periodical oscillations of the vocal folds with a complete glottis closure. In contrast, a glottal insufficiency (GI) represents an oscillation without glottis closure resulting in a breathy and weak voice. In this study, flow-induced oscillations of silicone vocal folds were modeled with and without glottis closure. The measurements comprised the flow pressure in the model, the generated sound, and the high-speed footage of the vocal fold motion. The analysis revealed that the sound signal for vocal fold oscillations without closure exhibits a lower number of harmonic tones with smaller amplitudes compared to the case with complete closure. The time series of the pressure signals showed small and periodical oscillations occurring less frequently and with smaller amplitude for the GI case. Accordingly, the pressure spectra include fewer harmonics similar to the sound. The analysis of the high-speed videos indicates that the strength of the pressure oscillations correlates with the divergence angle of the glottal duct during the closing motion. Physiologically, large divergence angles typically occur for a pronounced mucosal wave motion with glottis closure. Thus, the results indicate a correlation between the intensity of the mucosal wave and the development of harmonic tones.

Bayesian estimation of vocal function measures using laryngeal high-speed videoendoscopy and glottal airflow estimates: An in vivo case study

This study introduces the in vivo application of a Bayesian framework to estimate subglottal pressure, laryngeal muscle activation, and vocal fold contact pressure from calibrated transnasal high-speed videoendoscopy and oral airflow data. A subject-specific, lumped-element vocal fold model is estimated using an extended Kalman filter and two observation models involving glottal area and glottal airflow. Model-based inferences using data from a vocally healthy male individual are compared with empirical estimates of subglottal pressure and reference values for muscle activation and contact pressure in the literature, thus providing baseline error metrics for future clinical investigations.

Surgical Considerations for an Awake Tracheotomy During the COVID-19 Pandemic

Background: The current global COVID-19 pandemic is caused by the novel coronavirus Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2). Given that SARS-CoV-2 is highly transmissible, surgical societies have recommended that procedures with a high risk of aerosolization be avoided or delayed. However, some high-risk procedures, such as those related to head and neck malignancies, cannot always be delayed. Care must be taken during aerosol-generating procedures to minimize viral transmission as much as possible. Preoperative testing for COVID-19, limited operating room personnel, adequate personal protective equipment, and surgical technique are factors to consider for high-risk procedures. Methods: This article presents the case of an awake tracheotomy performed for a transglottic mass causing airway obstruction. Results: With detailed planning and specific techniques, the amount of aerosolization was reduced, and the procedure was performed as safely as possible. Conclusion: This case provides a template for future aerosol-generating procedures during respiratory pandemics.

[Effect of vertical anterior laryngectomy with pedicled sternohyoid flap for vocal cord reconstruction and glottal morphology]

Objective:To explore the effect of vocal cord reconstruction with sternohyoid muscle flap pedicled with vertical anterior laryngectomy. Method:The clinical data of 43 cases of laryngeal carcinoma were analyzed retrospectively. According to whether the vocal cords were reconstructed, they were divided into vocal cord reconstruction group and non reconstruction group. Among them, 20 patients in the reconstruction group were reconstructed with pedicled sternohyoid muscle flap and 23 patients in non-reconstruction group. In the non reconstruction group, the external membrane of thyroid cartilage was used to repair the wounds. Postoperative respiratory function, swallowing function, pronunciation function, postoperative prognosis, complications, and recurrence rate were compared between the two groups. Reconstruction of glottis after vocal cord reconstruction was evaluated by electronic laryngoscope and CT scan. Result:①Patients in both groups survived during the follow-up period. One patient in the non-reconstructed group had recurrence, and the reconstituted group had no relapse, 3 cases with complications occurred in the reconstruction group, including 2 cases with granulation tissue in the glottic area, 1 case with laryngeal fistula, and 2 cases with aspiration pneumonia were found in the non-reconstruction group. ②1 year postoperative tracheal cannula removal rate, gastric tube removal and pronunciation quality: the tracheal cannula removal rate was 100% in the two groups after surgery; the gastric tube removal time in the reconstruction group was（13.2±2.8） days, and （16.6±5.3） days in the non-reconstruction group （P<0.05）; reconstruction group had good pronunciation in 10 cases, moderate in 6 cases, and poor in 4 cases. Non-reconstructed group had good pronunciation in 4 cases, medium in 14 cases, and poor in 5 cases. Those with moderate or higher were compared no significant difference （P>0.05）, and those with good pronunciation were statistically different （P<0.05）. ③The transverse and anteroposterior diameter in reconstruction group was similar with the normal people （P>0.05）; however, the transverse and anteroposterior diameter in the non-reconstructed group was significantly different with that of the normal people （P>0.05）, the transverse diameter of the reconstructed group and the non-reconstructed group were compared with no significant difference （P>0.05）, but there was significant difference in the anteroposterior diameter between the two groups （P<0.05）. The area in both groups were different with the normal people （P<0.05）; ④Glottic area morphology: the two groups of patients showed different degrees of swelling in the arytenoid cartilage area, the shape of the glottic region in the reconstructed group was approximately triangular, and the glottic morphology in the non-reconstructed group was approximately circular. Conclusion:After vocal cord reconstruction, there were increased rate of tracheal cannula extubation, well covered wallowing and phonation function, and the quality of life of patients was improved.

Phonation threshold pressure using a 3-mass model of phonation with empirical pressure values

Understanding the control parameters that influence phonation threshold pressure can have important implications for ease of phonation. Using a computer model of phonation can aid in studying parameters not easily controllable through human experimental work and may provide a means of explaining variations seen across human participants. A vertical 3-mass computer model of phonation with empirical driving pressures was used to obtain phonation threshold pressures for a variety of prephonatory conditions that may be realistically produced by humans. The resulting phonation threshold pressures are reasonable compared to results from human studies and may extend beyond the range of phonatory control parameters studied in human experiments. In addition, the present work adds a formula for calculating phonation threshold pressure based on the prephonatory glottal angle, the tension of the vocal folds, and the prephonatory diameter. Of special interest is that, as the prephonatory angle of convergence increases from 0 degrees (the rectangular glottis condition), the phonation threshold pressure increases in a nearly linear fashion.

[Preliminary study of medialization thyroplasty for unilateral vocal fold immobility]

Objective:To explore the feasibility and effectiveness of medialization thyroplasty for the treatment of unilateral vocal fold immobility （UVFI）. Method:Eight UVFI patients were performed medialization thyroplasty under local anesthesia. We made a window in the thyroid cartilage under local anesthesia, then insert the preformed silicone implant. The paralyzed vocal fold was medialized to make the glottis closed. Fibrolaryngoscope video recording, subjective voice analysis and CT thin slice scan of larynx were done before and after surgery to evaluate closure of vocal cords, improvement of voice and position of implantation. Result:The preoperative and postoperative voice handicap index 30（VHI-30） of the 8 patients were 91.5（64.5, 97.5） and 22.5（5.0, 47.5） respectively, which showed statistical difference（P<0.05）. GRBAS results: The postoperative G, R, B, A were all smaller than preoperative ones, which showed statistical difference（P<0.05）; the pre and postoperative S was both 0. The fibrolaryhgoscope recording showed the preoperative and postoperative score of incomplete glottis closure was 1.0（1.0, 1.0） and 4.0（2.5, 5.0） respectively, which showed statistical difference（P<0.05）. Postoperative laryngeal CT showed significant vocal cord medialization on the affected side. Aspiration was significantly improved in 4 patients who were suffered from this symptom before the surgery. No complication occurred with the 8 patients during 5 to 48 months follow up. Conclusion:Medialization thyroplasty can effectively improve vocalization and quality of life in patients with UVFI.